Research on charge-discharge process of lithium ion battery pack with series connection

The voltage,internal resistance,capacity and temperature-rise of each individual battery in the Li-ion battery pack with series connection were tested during charge-discharge process,and their relationship was also investigated.The testing results indicate that with the increase of discharge rate and cycle times,the ununiformity of individual battery increases,including the relative overcharge and overdischarge,which causes the higher temperature-rise and lower residual capacity.The differences in resistance led to different heat generation of each individual battery,combined with different heat dissipation,and the module was chronically in non-uniform temperature field,which made the ununiformity of individual battery more serious.